How to decrease entity based lag on a server?

[RoboKast]

I currently have a pretty high powered machine that is more than capable enough to run a server of my size, but, for some reason entities are causing the TPS to drop to 15-17. Any suggestions for how I can keep this from happening?

I know that a lot of the issue has to do with people having large mob grinders, but we can't really get rid of spawners or anything like that.

Thanks!